I use a Phenom 2 X4 and have no problems at all.
Of course Intel is better, but it's also more expansive. There's nothing wrong with going for AMD except if you think you'll stall the CPU with a LOT of plugins. CPU benchmarks indicate this AMD is close to an
Intel Core i7-3770S.
http://www.cpubenchmark.net/cpu_lookup.php?cpu=AMD+FX-8350+Eight-Core&id=1780So I think it will be quite comfortable.
Concerning your power supply, you can find fanless PSU. They are more expansive,but not that much, and it's one fan you can't slow down less. 600W is overkill. 400W should be enough. (no big gaming GPU and they are the reason why more than 400W is needed). I have a 400W PSU with a radeon HD4550, 4 HDDs ,a 95W CPU, a UAD1 card and no problems.
Also check CPU coolers. Stock ones tend to be noisy, but not a lot more that a middle price "better one". Check reviews.
Concerning windows 7 or 8 both should work. The only reasons to get windows 7 is:
* You already own a licence.
* You don't like Windows 8 interface (a lot do)
* Your audio hardwares (soundcard,midi,DSPs,plugins) are old and do not support windows 8(plugins shouldn't pose problems unless they use outdated copy protections).
* You need to use legacy firewire drivers(my focusrite LiquidMix needs them)
Be careful,if you have a home/home premium edition,you won't be able to use more than 16Gb RAM. Only Pro version and up can use more.